Shock latch



Jan. 17, 1967 G. A. WILSON SHOCK LATCH Filed Oct. 29, 1964 United States Patent O 3,299,243 SHCK LATCH George A. Wilson, Media, lia., assignor to I-T-E Circuit Breaker Company, Philadelphia, Ia., a corporation of Pennsylvania Filed Oct. Z9, 1964, Ser. No. 407,393 5 Claims. (Cl. Z110-169) The instant invention relates to circuit protective devices and more particularly to novel shock latch means for use in impeding the movement of circuit breaker trip latches during periods in which the circuit breaker is exposed to shock or impacts from extraneous sources such that the shock latches may be used advantageously in naval applications and wherein they act to prevent false tripping of circuit breaker devices 'due to the shocks or impacts experienced by the circuit breaker structures.

While many circuit breaker installations are provided in commercial applications such as, for example, buildings or underground or outdoor sub-stations, there are many circuit breaker applications in which the circuit breaker apparatus will experience shock or impact from external sources. For example, in naval installations, the motion of the ship upon which the circuit breaker apparatus is installed due 4to storms of seas, enemy attack and any other possible sources may, and quite often does, have an adverse eiiect upon the circuit breaker tripper mechanisms.

Tripper mechanisms of circuit breakers are normally comprised of a relatively sensitive latch member which in its normal condition is positioned to latch a circuit breaker device in either its charged-to-open or chargedto-closed position. Movement of the circuit breaker latch means releases the tripping member to permit either high speed closing or high speed opening operation. The tripper members of such circuit breakers are relatively sensitive devices and may be caused to move due 'to shocks or impacts caused by external sources which, in turn, may cause the tripper member to unlatch, thereby causing a false operation of the circuit breaker apparatus.

It is a function of the device of the instant invention to provide a safe, reliable means for preventing false operation of a circuit Ibreaker tripper member while providing a novel shock latch means which is simple in design and assembly and may be readily attached to already existing circuit breakers :and which are so small as to occupy very little space within a breaker mechanism.

The shock latch of the instant invention is comprised of an unbalanced substantially U-shaped member pivotally mounted about its central portion to the circuit breaker housing and having two pointed edges of the central portion thereof positioned in close proximity to the circuit breaker tripper bar member. The arms of the U-shaped mem-ber secure spring loaded lever members which are spring loaded by a suitable bias means. The ends of these lever arms are carried in a suitable aperture within the circuit breaker housing. The shock latches, when undergoing movement due to shocks or external impacts, rotate about its pivot point causing one of its sharp edges to engage or snub the surface of the tripper bar member. In doing so the shock latch means moves against the spring biased lever arms which, in turn, cause the shock latch member to rebound and rotate in the reverse direction. This rebounding will occur several times until the biasing means brings the element back to rest, thereby impeding any rotating motion of the tripper latch. The shock latch will undergo such imbalance each time a shock or impact is experienced by the circuit breaker, then the shock latch will come to rest only after the shock or impact 'has subsided.

3,299,243 Patented Jan. 17, 1967 ICC By providing a plurality of shock latch means arranged at orientations relative to one another the protection against movement of the tripper bar member would be assured regardless of the direction which the shock has imparted upon the tripper bar.

Under normal circumstances, the shock latch means do not impose any load whatsoever upon the ktripper bar member and due to their design are very quick to reset in readiness -for operation which may 'be imposed by a subsequent shock or impact.

It can therefore be seen that the instant invention provides novel shock latch means for use in preventing the false operation of circuit breaker tripper bars. y

Another object of the instant invention is to provide novel shock latch means for use in circuit lbreakers and the like which is so designed as to prevent the movement of a circuit breaker .tripper mem-ber which is inuenced by a shock or impact caused by some external source.

Another object of the instant invention is to provide novel shock latch means for use in circuit breakers and the like which is so ydesigned as to prevent the movement of a circuit breaker tripper member which is influenced by a shock or impact caused by some external source and wherein the shock latch means imposes no load whatsoever upon the tripper member during normal operation thereof.

Still another object of the instant invention is to provide novel shock latch means for use in circuit breakers and the like comprising a pivotally mounted shock latch member positioned in close proximity to the circuit breaker tripper member for engagement therewith when imbalanced due to shock or impact from external sources to prevent move-ment of the tripper Imember due to such sources.

Still another object of the instant invention is to provide novel shock latch means-for use in circuit breakers and the like comprising a pivotally mounted shock latch member positioned in close proximity to the circuit breaker tripper member for engagement therewith when imbalanced due to shock or impact from external sources to prevent movement of the tripper member d-ue to such sources and wherein bias finger means are provided for rebounding and balancing said shock latch member.

Another object of the instant invention is to provide novel shock latch means for use in circuit -breakers and the like wherein iirst and second shock latch means are provided in predetermined angular relationship relative to one another so as to protect the circuit 4breaker tripper bar against external shock or impact wherein operation is assured regardless of the direction of the force upon the tripper bar generated by the external shock or impact.

These and other objects of the instant invention will become apparent when reading the accompanying description and drawings in which:

FIGURE 1 shows a perspective view of a shock latch designed in accordance with the principles of the instant invention.

FIGURE 2 shows the top view of the portion of the circuit breaker apparatus employing the shock latch of FIGURE 1.

FIGURE 3 shows a side elevational view of the lassembly of FIGURE 2 with one housing member being removed to expose all the elements thereof.

Referring now to the drawings, FIGURE l shows a shock latch 10 designed in accordance with the principles of the instant invention. The shock latch 10 is cornprised of a rigid metallic member 11 having a central portion 12 from which are disposed first and second arms 13 and 14. The central portion 12 is provided with an aperture 15 which extends through the entire length of the member 11.

The underside of central portion 12 is a generally arcuate surface 16 which meets the vertical sides from which the arms 13 and 14 are formed so as to form the relatively sharp corners of vertices 1'7 `and 18, respectively.

Each of the arms 13 and 14 are provided with an aperture 19 and 20, respectively, for receiving and positioning drive pin 21 which may be secured within these apertures 19 and 2i) in any suitable manner.

Mounted upon the drive pin 21 are irst and second lever arms 22 and 23, respectively, each having an aperture 24 and 25, respectively, for receiving the drive pin 21 therethrough. The lever arms 22 and 23 are biased against the surfaces of the arms 13 and 14 of member 11 by means of the helical biasing spring 26 through which drive pin 21 passes and which has its left and right-hand ends bearing against the lever arms 22 and 23, respectively. Each of the lever arms 22 and 23 are provided with a tapered ear or projection 22a and 23a, respectively, iat its forward end thereof for a purpose to be more fully described.

The application and operation of the shock means of FIGURE 1 can best be understood from a consideration of the FIGURES 2 and 3 which show the manner of installation and use of a shock latch in cooperation with a circuit breaker tripper member.

The installation 100 shown therein does not display a circuit breaker in full detail but, for the purpose of simplicity, simply shows a circuit breaker latch member 30 which is mounted for rotation upon a shaft 31 which has ian arcuate shape portion 32 and is provided with first and second projections 33 and 34. The latch member 30, shown best in FIGURE 3 has a flange 33a providedon projection 33 for positioning and securing the first end 35a of a torsion spring 35 which is wrapped around a circular central portion 36 of member 30* and which has its .opposite end 35b bearing against a stop member C. The stop member C bears against the edge 33a of projection 33 so as to prevent the tripper latch member 30 from rotating in the counterclockwise direction as shown by arrow 36. The torsion spring 35 generally prevents the tripper latch member 30 from rotating in the clockwise direction as shown by arrow 37.

While the entire circuit breaker mechanism is not shown, it is suflicient to understand that the circuit breaker will be tripped, i.e., operated rapidly to the open or disengaged position upon movement of a trip roller 38 generally in the direction shown by arrow 39. Motion in the direction 39 is prevented when the projection 34 of member 30 is in the position shown in FIGURE 3. Circuit breakers operating in this manner are substantially well known in the prior art. Typical circuit breakers employing the device of this type being set forth in:

U.S. Patent 2,961,068, issued Nov. 22, 1960, to C. I. Yarrich, et al., entitled Control Mechanism for Spring Close Circuit Breakers, and

U.S. Patent 2,961,067, issued Nov. 22, 1960, to R. V. Starr, entitled Electrically Operated Stored Energy System for Circuit Breakers, and

U.S. Patent 2,849,570, issued Aug. 26, 1968, to W. M. Scott, Ir., entitled Short Time Delay Defeater During Closing Stroke of Circuit Breaker, and

U.S. Patent 2,849,569, issued Aug. 26, 1958, to W. M. Scott, J r., entitled Selective Trip Circuit Breaker With Instantaneous Trip During Closing, all assigned to the assignee of the instant invention.

The trip latch member 30 rotatably mounted upon shaft 31 is positioned and supported by the support elements 40 and 41 shown in FIGURE 2 which form part of the circuit breaker mechanism housing. The arrangement 100 is shown as being provided with first and second shock latch assemblies 10 and 10 of the type shown in FIGURE 1. Both shock latch assemblies 10 and 10 are pivotally mounted to the vertical housing support members 40 and 41 by the pivot pins 42 and 43 which pass through the openings and 15 provided in the members 10 and 10', respectively. The pins 15 and 1S (only one of which is shown in FIGURE 2) are then secured to the vertical support walls 40' and 41 in any suitable fashion. A spacer member such as the spacer member 44 is provided on pin 15 and between walls 40 and 41 in order to relatively accurately position the shock latch assembly 10. It should be understood that a similar spacer member may be provided for the shock latch assembly 10, the view of member 10 being omitted from FIGURE 2 for purposes of simplicity only.

The shock latch assemblies 10 and 10' are positioned so that their notably sharp corners 17-18 and 17'-18, respectively, are positioned in very close proximity to the arcuate edge 32 of the tripper latch member 30. Each latch assembly is still further positioned so that the iingers 22a-23a are positioned within an aperture 46 provided in vertical support wall 40, for example, it should be understood that a similar arrangement is provided for the shock latch 10 with this view having been omitted for purposes of simplicity only.

The shock latches 10 and 10 ane so positioned as to be angularly displaced by substantially relative to one another for a purpose to be more fully described.

The operation of the shock latch 10 is as follows (it being understood that the operation of shock latch assembly 10 would be substantially identical) Let it be assumed that a shock or impact is imposed upon the apparatus of FIGURES 2 and 3 due to some external source. Let it be assumed that thedirection of the force caused by this shock or impact is such as to cause the shock latch 10 to rotate in the clockwise direction, as shown by arrow 37. Since the latch assembly 10 `is free to pivot about a pivot pin 43, the assembly 10' will undergo clockwise rotations until its sharp edge 17' makes physical engagement (i.e., snubs) with the arcuate surface 32 of tripper latch member 30. The shock latch, on snubbing arcuate surface 32 with its sharp edge 17 is caused to immediately rebound so that the sharp edge 1S snubs the arcuate surface 32. This rebounding will occur several times until the centering spring 26 brings the shock latch 10 back to rest position thus impeding any rotating motion of the tripper latch member 30. The resetting of shock latch 10' presupposes the fact that any vibration or impact suifered by the structure has subsided. The snubbing of the arcuate surface 32 by shock latch corner 17 and 13 will again take place upon occurrence of subsequent impacts or shocks experienced by the apparatus 100.

The surface of arcuate portion 32 may be lightly knurled or roughened for more positive effect, but even in the event of failure of the centering spring 26 the tripper latch member 30 can still be forced to rotate by the closing solenoid (not shown) by which it rotates. Since some minimum clearance is normally maintained between the sharp corners 17 and 18 and t-he arcuate surface 32, no additional loading is imposed upon the tripper latch member under normal closure conditions.

While the description above has `been made with specific reference to the shock latch assembly 10', it should be understood that the shock latch -assembly 10 operates in the same manner. Also, the provision of first and second latches 10 and 10 substantially at right angles to one another act to guarantee that any shock or impact experienced by the structure 100 will cause at least one of the shock latch structures 10 or 10 to become operative regardless of the direction of the force imposed upon the structure 100 due to exterior shocks or impacts.

It can be seen from the foregoing description that the instant invention provides a novel shock latch assembly which protects a tripper latch member against rotational movement due to shocks or impacts from external sources which may, in turn, lead to a false tripping operation. Practical shock latches designed in accordance with the principles of the instant invention have been constructed and typical dimensions of such structures are, length s/s,

height Mi" and Width It can clearly be seen that practic-al embodiments are extremely small, thereby occupying very little space within la breaker tripping structure, While at the same time providing the much needed function of protecting the tripper latch means against the possibility of accidentally tripping the circuit breaker.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. Shock latch means for use in preventing false operation of. circuit breaker trip latch members comprising an unbalanced rigid body having first and second arms disposed in a first direction from said body; one surface of said body being generally arcuate and terminating in first and second corners facing in a second direction opposite said first direction; means for pivotally mounting said body at a point intermediate said arms and said corners; spring loaded finger means for centering said latch means.

2. Shock latch means for use in preventing false operation of circuit breaker trip latch members comprising an unbalanced rigid -body having first and second arms disposed in a first direction from said body; one surface of said lbody being generally arcuate -and terminating in first and second corners facing in asecond direction opposite said first direction; means for pivotally mounting said body at a point intermediate said arms and said corners; spring loaded finger means for centering said latch means; said spring loaded finger means comprising first and second finger members; a pivot pin securing each of said finger means to the arms of said rigid body; spring means mounted upon said pivot pin biasing said first and second finger members toward said first and second arms, respectively.

3. A circuit breaker trip latch assembly comprising a shaft; a trip latch member Irotatably mounted to said shaft and having an arcuate surface; at least one shock latch means of the type described in claim 1 mounted with its first and second corners in close proximity to said trip latch member arcuate surface; means for receiving said first and second finger members enabling said shock latch means to `be repositioned.

4. A circuit breaker trip latch assembly comp-rising a shaft; a trip latch member rotatably mounted to said shaft and having an arcuate surface; at least one shock latch means of the type described in claim 1 mounted with its first and second corners in close proximity to said trip latch lmember arcuate surface; said pivotal mounting means `being substantially parallel to said shaft; means for receiving said first and second finger members enabling said shock latch means to be repositioned.

5. A circuit breaker trip latch assembly comprising a shaft; a trip latch member rotatably mounted to said shaft and having an arcuate surface; first and second shock latch means of the type described in claim 1 mounted with its first and second corners in close proximity to said trip latch member arcuate surface; means for receiving said spring loaded finger means enabling said shock latch means to be repositioned; said first and second shock latch means being angularly disposed at approximately relative to one another to provide protection against false operation of said trip latch member regardless of the direction of Iany forces of shocks or impacts from external sources.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner. 

1. SHOCK LATCH MEANS FOR USE IN PREVENTING FALSE OPERATION OF CIRCUIT BREAKER TRIP LATCH MEMBERS COMPRISING AN UNBALANCED RIGID BODY HAVING FIRST AND SECOND ARMS DISPOSED IN A FIRST DIRECTION FROM SAID BODY; ONE SURFACE OF SAID BODY BEING GENERALLY ARCUATE AND TERMINATING IN FIRST AND SECOND CORNERS FACING IN A SECOND DIRECTING OPPOSITE SAID FIRST DIRECTION; MEANS FOR PIVOTALLY MOUNTING SAID BODY AT A POINT INTERMEDIATE SAID ARMS AND SAID CORNERS; SPRING LOADED FINGER MEANS FOR CENTERING SAID LATCH MEANS. 